PC Hijack

A friend had his PC "hijacked" last week. He clicked a Google link (doesn't know what it was - he was looking to buy a car). The next thing he seems to be linked to a child porn website, then gets a message saying "the police are aware of your web address - press this button to remove the evidence"

He had the sense not to press the button, but this thing has burrowed into his sytem, and he couldn't remove it. Reloaded Windows, everything, it kept coming back.

He was so shaken by it he's bought a new PC, changed his ISP, etc etc, and is reformatting the disk of the old machine for re-use elsewhere, but he's still worried he hasn't got rid of it even now.

In a way he left himself open to it because he had no AV software, but this was so nasty I'm surprised I haven't seen it written up in the press.

Is this a known problem? Is it common now? Does anyone know how to get rid of it? I'd be grateful for any views.

Sounds very much like Spyware to me. It is basically like a cookie which reports home when you are on the net and calls it's own sites (usually porn), it can also connect to a premium rate number without you even knowing it.